Many Mexicans wear mariachi costumes on Saturday evening to commemorate the launch of the revolt against Spanish rule on September 16, 1810.

Lisa Sanchez, director of Mexicans United Against Delinquency, described the shooting as a “piercing portrait” of Mexico.

She said the fact that the shooting happened in a crowded public square demonstrates that impunity prevails in the country.

On Saturday night, President Enrique Pena Nieto is set to shout “Viva Mexico” — or “Long Live Mexico” — shortly before midnight from a balcony of the National Palace.

Thousands crowd into Mexico City’s central Zocalo square every year to hear the shout, and the celebration usually spills into Garibaldi Plaza.

Videos circulating on social media showed musicians in the plaza playing their music around the time of the shooting.

In one video, a man plucking a large harp continues to belt out the Mexican civil war anthem “La Cucaracha” as dozens of gunshots can be heard in the background, though it is not clear the musicians heard them.

In another, brass instruments and melancholic voices fill the air as the flashing lights of police vehicles descend on the plaza.